The present invention relates to a mulcher, and more particularly to an apparatus for continuously paying off a strip of film and laying down the strip over a ridge longitudinally thereof while covering the laid-down strip with soil on its opposite side portions longitudinally thereof.
Mulching has been widely accepted practice for growing plants, such as tobacco, lettaces, etc.
To assure sound growth of crops and protect them from frost, wind and rain, a strip of plastics film, sheet or the like is laid down over a ridge on the ground longitudinally thereof, and the laid-down mulch is covered with soil on its opposite side portions longitudinally thereof to prevent removal of the mulch.
As machines for applying mulches mechanically and efficiently, there are mulchers of the self-propelling type and those adapted to be attached to and pulled by a tractor with use of a three-point link or the like. The mulchers of either type consist essentially of a ridge shaping assembly, a roll suspending or supporting assembly for supporting a roll of film strip at right angles with the ridge, namely, with the direction of travel of the mulcher rotatably about its axis, a pair of opposite wheels for pressing opposite side portions of the strip against the ground to pay off the strip, and a pair of soil applicators for covering the paid-off strip with soil on its opposite side portions longitudinally thereof.
With conventional roll supporting or suspending assemblies, both ends of the roll, namely, both ends of a spool or support spindle are fixedly supported by bearing portions attached to the frame of the mulcher, so that with the progress of mulching operation, the diameter of the roll invariably decreases, incessantly altering the peripheral speed of the roll and also the position where the strip is paid off the roll to vary the length of travel of the strip from this position to the position where it is pressed against the ground by the pair of pressing wheels. Since the strip can be laid down on the ridge accurately and smoothly only when under tension, variations in the length of travel of the strip are objectionable. Especially when the operation is performed in a strong wind, variations in the distance of travel will partly loosen the strip and consequently produce wrinkles or folds in the strip laid down on the ridge. Such objections must be avoided. In continental areas as in the U.S. and Canada, ridges have very large lengths and require the use of rolls of large diameter. The operation therefore involves marked variations in the above-mentioned peripheral speed and position of paying off. It is accordingly critical to eliminate such variations.
Another important problem encountered in the mulching operation is to prevent the rise of the pair of pressing wheels to thereby hold the strip under uniform tension over the ridge and facilitate the subsequent application of soil.
The pressing wheels of the prior art are rotatably supported as positioned in parallel to each other. The wheels are therefore unable to hold the strip properly tensioned uniformly over the entire width of the ridge. If the wheels have a tread of soft sponge or the like, it would be difficult to force the strip into the ground.
Another important problem experienced with the mulching operation is to prevent the removal of the laid-down strip due to wind or rain and also the removal of the strip-holding soil covering from the strip. Soil applicators heretofore used are of the disc rotor type or shoe type. These applicators are adapted to apply soil to the laid-down strip only at the bottom of the ridge to hold the strip. If the mulch is used on a sandy ground where it rains heavily as in some of the continental areas of the U.S. and Canada, the soil covering with easily flow away. Further if water lodges in the furrows of a dry field, the ridges as well as the soil covering will collapse and flow away.
Another important problem involved in the mulching operation is to prevent the collapse of the ridge by fully compacting the soil, whereas conventional ridge shaping devices are uable to ensure sufficient compaction of the soil if it is sandy, or permit collapse of ridges of clayey soil in areas where it rains heavily. Such objection is more likely to occur when high ridges are to be mulched.